In between all of the TV ads from the presidential campaigns of Barack Obama and John McCain, you may have noticed some new political ads cropping up by groups with funny-sounding names.

Some of the groups behind the latest ads include Vets for Freedom, Born Alive Truth PAC and the American Issues Project.

The shorthand term for these messages is "527 ads" — because some of the advertisers operate under Section 527 of the tax code.

The quintessential 527 was Swift Boat Veterans for Truth four years ago. Now, most groups don't use the 527 status.

But however they set themselves up, most of the groups can raise unlimited sums from wealthy donors. Some of them can keep their finances secret. And all of them typically focus on tearing down the opposition.

Early on, both candidates tried to discourage this whole business. Obama's campaign even told its fundraising team not to associate with 527s.

But it turns out the candidates don't have much say in the matter.

Sampling The Independent Groups

Take Brave New Films, a progressive group. Right now, it's working up an ad on McCain that insinuates that his health is worse than we know and demands that he release all of his medical records.

The founder of Brave New Films, Hollywood director Robert Greenwald, says his group fills a niche in the liberal message network.

"Character as it affects policy, rather than the fifth paragraph in the global warming plank — which is important, it's just not our job," he says.

And there's the American Issues Project. It recently ran an ad insinuating that Obama has close ties to a Vietnam War-era radical militant who was a fugitive from the FBI.

"American Issues Project has had people of incredible financial means who have said this was very effective. This is helpful. I'm interested to talk more," he says.

But not everything is running full throttle among the independent groups.

Laws Governing Independent Groups

The laws have changed since 2004, making it trickier to operate. On top of that, cash flow is down dramatically. Each side is convinced the other is spending more.

Republican consultant Eddie Mahe says that many big-ticket donors are watching but so far not playing. He says they're leery of McCain, and they're definitely not excited about Sarah Palin.

"I'm not talking about rank-and-file voters out there," he says. "I'm talking about that very small group of people who understand independent expenditures and have the capacity to write at least $50,000 to $100,000 checks."

On the Democratic side, strategist Tom Matzzie says time is running out for groups that aren't already at work. He says they're going to find that all the TV time has been bought up.

"Or perhaps the legal risks just aren't worth it for something that's only going to happen for a week or two, and donors aren't interested," he says.

Beyond The TV Ads

There's more to these groups than television. In late October, voters in swing states will start getting direct mail, phone calls and push polls.

The messages will be even harsher than the TV ads. The messengers might be groups already on the field, or some that haven't been heard from yet.

Political scientist David Magleby of Brigham Young University has been studying the influence of these outside operators since the 1990s. He says independent groups save the worst for last.

"A group might raise the issue of Sen. McCain's age. Or a group may say something about race. I think abortion and religion are likely to be issues in the last week, especially with the Palin candidacy," he says.

The reason for these last-minute below-the-radar attacks — and all that preceded them?

"I think it goes way beyond whether you like Obama or McCain to ideology and agenda-setting," Magleby says.

There are simply too many people, with too much at stake, to let the attacks go unmade.